Multimedia

The media subsystem with its remote control, TV, video and webcam drivers now includes the media controller subsystem (e.g. 1, 2, 3); it improves the way the userspace can utilise the video hardware functions available in SOCs (Systems-on-a-Chip) and is described in an article on LWN.net.

Also new is a driver for the Technisat USB 2.0 DVB-S/S2 receiver and some code to support the DiBcom 9000 – a DVB-T tuner designed for use in mobile devices. Another addition to the kernel is the nw80x gspca subdriver that addresses webcam chips by Divio. These chips are used by a variety of manufacturers, for instance, they are included in Logitech's QuickCam Pro model with a dark focus ring. For the "3com homeconnect" webcam, the kernel now offers a completely rewritten V4L2 gspca driver that is said to offer better performance than the older V4L1 vicam driver. In his main Git-Pull request for 2.6.39, media subsystem maintainer Mauro Carvalho Chehab offers a good overview of the other changes to this subsystem.

Staging

The developers have added the psb_gfx graphics driver for the GMA500, a graphics core that was previously considered a big problem under Linux. It is included in Intel's US15W ("Poulsbo") chipset, which was originally designed for the embedded market but is used in netbooks by some manufacturers. Since the introduction of the initially very rudimentary code, the driver has already been improved in many areas (1, 2); however, more work is required and the driver has, therefore, been added to the staging area, as was originally intended – this area contains drivers and other code that don't meet the developers', or the kernel hackers', quality requirements.

A mouse driver developed by Microsoft for Hyper-V has also been added to this area. Recently, numerous changes have been made to the Hyper-V drivers that have been part of the kernel for some time. It seems as if the Microsoft developers have been investing considerably more energy in fixing quality issues so that the drivers can leave the staging area; for a long time, Microsoft didn't appear to take the open source drivers very seriously and no, or very little, progress was made.

Further staging components include the transcendent memory infrastructure, described on LWN.net, and the zcache feature that is based on it – zcache originated from the zram environment and tries to use the system's working memory more efficiently by compressing the page cache. Having thought about including cleancache after the end of the latest merge window, Linus Torvalds has decided not to merge the feature. Cleancache was created in the same context and is required for certain tasks by zcache; whether the feature will follow in 2.6.40 is currently still unclear (1, 2).

Platform drivers

A driver for SABI has managed to leave the staging area. SABI is a Samsung interface that allows many of the netbooks and notebooks released by the manufacturer in recent years to inform the operating system of such user events as the pressing of function keys – for example the keys that regulate display brightness or sound volume.

The developers have also added a driver for processing the WMI events created by various all-in-one Dell systems when a volume control key is pressed. The .39 kernel also includes a driver for recent ASUS notebooks that use WMI to tell the operating system about function key events; this driver was created from the WMI driver for Eee PCs.

In brief

The USB code now supports USB 3.0 hubs (1, 2). During the development of version .39, kernel hacker Mauro Carvalho Chehab presented a "usbmon capture and parser script" on the LKML that allows developers to connect a USB sniffer – which he apparently needed for developing a TV driver. In the course of the discussion, it was pointed out to the media subsystem maintainer that similar software already exists.